Well, no. But the latest research suggests the health risk from occasional use is mild, and it might ease certain ills

I never smoked pot in junior high because I was convinced it would shrivel my incipient manhood. This was the 1980s, and those stark this-is-your-brain-on-drugs ads already had me vaguely worried about memory loss and psychosis. But when other boys said pot might affect our southern regions, I was truly terrified. I didn't smoke a joint for the first time until I was 21.

By 12th grade, about half of young Americans have tried marijuana, which put me in the geeky other half. I used to think this was a good thing, since I never developed a taste for pot and...